From: David Mosberger-Tang <David.Mosberger@acm.org>
Date: Tue, 26 Jul 2005 05:23:00 +0000 (-0700)
Subject: [IA64] Fix race in mm-context wrap-around logic.
X-Git-Tag: v2.6.14-rc1~1019^2~13^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=badea125d7cbd93f1678a95cf009b3bdfe6065cd;p=pandora-kernel.git

[IA64] Fix race in mm-context wrap-around logic.

The patch below should fix a race which could cause stale TLB entries.
Specifically, when 2 CPUs ended up racing for entrance to
wrap_mmu_context().  The losing CPU would find that by the time it
acquired ctx.lock, mm->context already had a valid value, but then it
failed to (re-)check the delayed TLB flushing logic and hence could
end up using a context number when there were still stale entries in
its TLB.  The fix is to check for delayed TLB flushes only after
mm->context is valid (non-zero).  The patch also makes GCC v4.x
happier by defining a non-volatile variant of mm_context_t called
nv_mm_context_t.

Signed-off-by: David Mosberger-Tang <David.Mosberger@acm.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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